JPH08334142A - Gas filled cylinder rod guide - Google Patents

Abstract

PURPOSE: To reduce a dimensional error after molding and to improve heat resisting rigidity by molding a rod guide of aromatic polyamide resin containing specified quantity of a fiber reinforcing agent. CONSTITUTION: A rod guide 3 is molded of aromatic polyamide resin containing 45-65% of a fiber reinforcing agent. The aromatic polyamide resin constituted of a constitutional unit induced from dicarboxylic acid and diamine, the dicarboxylic acid contains aromatic dicarboxylic acid as an essential component, and telephthalic acid is favourably contained as the aromatic dicarboxylic acid. Additionally, inorganic fiber of glass fiber, titanic acid potassium fiber, metal coated glass fiber, etc., is used as the fiber reinforcing agent. The rod guide 3 is molded by compression molding, injection molding, etc. In the aforementioned constitution, it is possible to manufacture the rod guide 3 more easily and at lower cost than sintered metal, a dimensional error after molding is less and its roundness is excellent, and the rod guide 3 is also excellent in rigidity at 110 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, an opening / closing part of a hatchback door of an automobile, an operating part of a control panel of an injection molding machine or a machine tool, an opening / closing part of a panel or a lid of office equipment, a sitting position of an office chair. The present invention relates to a rod guide for a gas-filled cylinder used for adjustment and the like.

[0002]

2. Description of the Related Art A gas filled cylinder is shown in FIG.
The cylinder 1 and the rod attached to the end of the cylinder
It is slidably attached to the guide 3 and the cylinder 1, and
To the piston 5 with a through hole 4 through which
Pis that is fixed and slidably inserted into the rod guide 3.
It consists of a ton rod 6 and several tens of kg / cm in the cylinder.²
The compressed gas is filled into the piston, and the piston 5
Area A on the opposite side of rod 6₁Is the area on the piston rod side
A₂The cross-section integral of the piston rod 6 is larger than
Therefore, if the gas pressure in the cylinder is p, the piston
Force P acting on the surface opposite to the pad 6₁= PA₁Is piss
Force P acting on the surface on the ton rod side₂= PA ₂Greater than
Therefore, it is always pushed in the direction of the arrow in the figure. However
The force required to move the piston 5 is P₁And P₂Of the power of
Since the difference is small, only a small amount is required, and therefore the various devices mentioned above
Opening and closing of equipment and equipment and position adjustment are performed without force, and
Due to pressure loss and friction loss of gas passing through the through hole 4,
The resistance to the movement of pin 5 causes shock
Acts as a buzo bar, causing shock when opening and closing
There is no such thing.

[0003]

The rod guide used in the above-mentioned gas-filled cylinder has excellent compressive strength so that it can withstand high internal pressure, excellent dimensional accuracy, and the cylinder after assembly. 110 degrees around
In the above, since it is required to have excellent heat resistance and rigidity for baking coating, sintered metal has been used exclusively in the past.

It is an object of the present invention to provide a rod guide which can be easily manufactured by a usual injection molding method, can be obtained at a lower cost than sintered metal, and has excellent heat resistance and rigidity.

[0005]

SUMMARY OF THE INVENTION The present invention therefore provides a fiber reinforcement.
It is intended to provide a rod guide molded from an aromatic polyamide resin containing 5 to 65%. The aromatic polyamide resin used in the present invention comprises a structural unit derived from (i) dicarboxylic acid and (ii) diamine.

The (i) dicarboxylic acid forming the aromatic polyamide resin contains an aromatic dicarboxylic acid as an essential component, and as the aromatic dicarboxylic acid, preferably (ia) terephthalic acid. There is. Further, this (i) dicarboxylic acid may contain (i-b) aromatic dicarboxylic acid other than terephthalic acid, and further (i-c) aliphatic dicarboxylic acid.

Examples of the aromatic dicarboxylic acid other than terephthalic acid (ib) include isophthalic acid, 2-methylterephthalic acid, naphthalenedicarboxylic acid, and combinations thereof. Of these, isophthalic acid is preferred. Specific examples of the (ic) aliphatic dicarboxylic acid include aliphatic dicarboxylic acids having an alkylene group having 2 to 20 carbon atoms, preferably 4 to 12 carbon atoms, and examples thereof include succinic acid, adipic acid, and azelaic acid. , Sebacic acid, and combinations thereof. Of these, adipic acid and sebacic acid are preferable.

Further, as described above, (i) a diamine which forms an aromatic polyamide together with a dicarboxylic acid, a diamine (ii) is a linear alkylene diamine having 4 to 18 carbon atoms and / or 4 to 4 carbon atoms having a side chain alkyl group. It is preferably 18 alkylenediamines. Such (ii-
a) Specific examples of the linear alkylenediamine having 4 to 18 carbon atoms include 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1, 9-Diaminononane, 1,10-Diaminodecane, 1,11
— Diaminoundecane, 1,12-diaminododecane, and combinations thereof.

Of these, 1,6-diaminohexane, 1,
8-diaminooctane, 1,10-diaminodecane and 1,12-diaminododecane are preferable, and 1,6-diaminohexane is particularly preferable. The alkylenediamine having a side chain alkyl group (ii-b) is specifically 1-butyl-1,2
-Diamino-ethane, 1,1-dimethyl-1,4-diamino-butane, 1-ethyl-1,4-diamino-butane, 1,2-dimethyl
-1,4-Diamino-butane, 1,3-Dimethyl-1,4-diamino
-Butane, 1,4-dimethyl-1,4-diamino-butane, 2,3-
Dimethyl-1,4-diamino-butane, 2-methyl-1,5-diaminopentane 2,5-dimethyl-1,6-diamino-hexane 2,4-dimethyl-1,6-diamino-hexane 3,3- Dimethyl-1,6-diamino-hexane 2,2-dimethyl-1,6-diamino-hexane 2,2,4-trimethyl-1,6-diamino-hexane 2,4,4-trimethyl-1,6-diamino -Hexane 2,4-diethyl-1,6-diamino-hexane 2,3-dimethyl-1,7-diamino-heptane 2,4-dimethyl-1,7-diamino-heptane 2,5-dimethyl-1,7 -Diamino-heptane 2,2-dimethyl-1,7-diamino-heptane 2-methyl-4-ethyl-1,7-diamino-heptane 2-ethyl-4-methyl-1,7-diamino-heptane 2,2 , 5,5-Tetramethyl-1,7-diamino-heptane 3-isopropyl-1,7-diamino-heptane 3-isooctyl-1,7-diamino-heptane 1,3-dimethyl-1,8-diamino-octane 1,4-dimethyl-1,8-diamino- Octane 2,4-dimethyl-1,8-diamino-octane 3,4-dimethyl-1,8-diamino-octane 4,5-dimethyl-1,8-diamino-octane 2,2-dimethyl-1,8- Diamino-octane 3,3-dimethyl-1,8-diamino-octane 4,4-dimethyl-1,8-diamino-octane 3,3,5-trimethyl-1,8-diamino-octane 2,4-diethyl- Among these, 1,8-diamino-octane 5-methyl-1,9-diamino-nonane, and combinations thereof, among these, the main chain has 4 to 10 carbon atoms and 1 carbon atom. Alkylenediamines having 1 to 2 side chain alkyl groups of .about.2 are preferable, and 1,6-diaminohexane or 2-methyl-1,5-diaminopentane is particularly preferable.

The number of carbon atoms in the description of the alkylenediamine having a side chain alkyl group (ii-b) means the number of carbon atoms of the main chain alkylene group and the number of carbon atoms of the side chain alkyl group unless otherwise specified. And the total. The aromatic polyamide resin used in the present invention is composed of structural units derived from (i) dicarboxylic acid and (ii) diamine as described above, and (i) 100 mol of structural units derived from dicarboxylic acid. %, The constituent unit (a) derived from terephthalic acid is 30 to 100 mol%, preferably 45 to 100 mol%, and more preferably 6
A structural unit (b) introduced from an aromatic dicarboxylic acid other than terephthalic acid and / or a structural unit (c) introduced from an aliphatic dicarboxylic acid in an amount of 0 to 100 mol%.
Is preferably contained in an amount of 0 to 70 mol%, preferably 0 to 55 mol%, and more preferably 0 to 40 mol%.

A polyamide having a content of the structural unit (c) derived from an aliphatic dicarboxylic acid of more than 70 mol% has a high water absorption rate, and a molded article obtained from such a polyamide has a large dimensional change due to water absorption. Sometimes.
The aromatic polyamide resin used in the present invention contains a small amount, usually 5 mol% or less, of a constitutional unit derived from a tribasic or higher polyvalent carboxylic acid such as trimellitic acid or pyromellitic acid. May be.

Further, the aromatic polyamide resin used in the present invention comprises an aromatic polyamide containing a structural unit (a) derived from terephthalic acid as a dicarboxylic acid as a main structural unit and a dicarboxylic acid. It may be a mixture with an aromatic polyamide containing a structural unit (b) derived from isophthalic acid as a main structural unit. The aromatic polyamide resin used in the present invention has an intrinsic viscosity [η] measured in concentrated sulfuric acid of 30 ° C. of 0.5 to 3.0 dl / g, preferably 0.5 to 2.8 dl / g, and particularly preferably 0.6 to 2.5 dl. / g is preferable.

The aromatic polyamide resin having the above-mentioned specific structure is excellent in moldability, particularly excellent in heat resistance, and has a low water absorption. Further, the glass transition temperature (Tg) in the amorphous part of this aromatic polyamide resin
Is higher than the glass transition temperature of the conventionally used aliphatic polyamide, usually 80 ° C. or higher, preferably 90
~ 150 ° C. Since the glass transition temperature in the non-crystalline portion is high as described above, a molded article formed by including the aromatic polyamide resin does not become in a molten state even when it is exposed to high temperature, and its dimensions do not easily change. .

The aromatic polyamide resin used in the present invention can be produced by polycondensing the above-mentioned (i) dicapronic acid and (ii) diamine.
Specifically, first, the amount of terephthalic acid (i
The dicarboxylic acid (i) and the diamine (ii) containing -a) as essential components are heated under pressure in a neutral medium in the presence of a medium such as sodium hypophosphite to produce a polyamide precursor. Then, the polyamide precursor can be produced by melt-kneading. When producing the polyamide precursor, a molecular weight modifier such as benzoic acid may be added.

Fiber reinforcing agents used in the present invention include glass fibers, potassium titanate fibers, metal-coated glass fibers,
Inorganic fiber reinforcing agents such as ceramics fibers, wollastonite, carbon fibers, metal carbide fibers and hardened metal fibers are used. The surface of such a fiber reinforcing agent may be treated with a silane compound such as vinyltriethoxysilane, 2-aminopropyltriethoxysilane, 2-glycidoxypropyltrimethoxysilane. Among these, glass fiber is particularly preferable because it has the best reinforcing effect.

In the polyamide composition of the present invention, in addition to the above components within the range that does not impair the object of the present invention, a heat resistance stabilizer, a weather resistance stabilizer, a plasticizer, a thickener, an antistatic agent, a release agent, Various known compounding agents such as pigments, dyes, inorganic or organic fillers, nucleating agents, carbon black, talc, clay, and acid-free compounds such as mica may be added. In order to obtain the composition of the aromatic polyamide resin and the fiber reinforcing agent used in the present invention, various known methods, for example, a method of mixing with a Hensiel mixer, a V blender, a ribbon blender, a tumbler blender, or after mixing, Single screw extruder,
A method of granulating or powdering after melt-kneading with a multi-screw extruder, a kneader, a pan-parry mixer or the like may be adopted.

The rod guide of the present invention can be molded by compression molding, injection molding or the like.

[0018]

Example: 70 mol% terephthalic acid, 30 isophthalic acid
Cylinder temperature 340 ° C., mold temperature 120 ° C., injection from a composition (specific gravity 1,63) consisting of 50 parts by weight of an aromatic polyamide resin composed of 100% by mol of hexamethylenediamine and 50 parts by weight of glass fiber. Speed, medium speed (5
0%), injection pressure, medium pressure (800-1000Kg / c
m ² ), a rod guide having the shape shown in Fig. 1 was injection-molded. The roundness (dimensional error) after molding was 2%, the rigidity at room temperature was 17,000 MPa, and the rigidity at 110 ° C was 1
It was 2,000 MPa. Using this molded product as a rod guide of the gas-filled cylinder, when the piston rod was reciprocated 2000 times, the crack occurrence rate and the gas leakage occurrence rate of the rod guide were tested.
The crack occurrence rate was 0 and the gas leakage occurrence rate was also 0.

As the gas filled in the cylinder used in the above test, air pressurized to several tens of kg / cm ² was used, and the presence or absence of cracks was visually inspected. It judged by reading the pressure of the pressure gauge attached to the cylinder. Comparative Example 1 A rod guide of FIG. 1 was injection-molded from a composition comprising 60 parts by weight of glass fiber and 66,50 parts by weight of nylon. This rod guide has a roundness (dimensional error) of 4% after molding and a rigidity at room temperature of 15,000 MPa, 110
The rigidity at ℃ was 5,000 MPa. Using this rod guide for a rod guide of the same gas-filled cylinder as in the example, the crack occurrence rate and the gas leak occurrence rate were tested in the same manner as in the example. The crack occurrence rate was 0, but the gas leak rate was 0. Occurred 0.5%.

Comparative Example 2 A rod guide was injection-molded from the same aromatic polyamide resin as in Example except that the glass fiber content was 40% by weight. The roundness (dimensional error) of the rod guide after molding is 5%, the rigidity at room temperature is 13,000 MPa, 110
The rigidity at ° C was 9,000 MPa. Using this rod guide for a rod guide of the same gas-filled cylinder as in the example, the crack occurrence rate and the gas leakage occurrence rate were tested in the same manner as in the example. The crack occurrence rate was 1% and the gas leakage was 3%. Occurred.

The above results are shown in Table 1 below.

[0022]

[Table 1]

As described above, according to the rod guide of the embodiment, neither cracking nor gas leakage occurs,
Further, the roundness after molding and the rigidity at 110 ° C. are Comparative Example 1,
Both were superior compared to 2.

[0024]

EFFECTS OF THE INVENTION According to the rod guide of the present invention, since it is a molded product made of an aromatic polyamide resin containing a fiber reinforcing agent, it is easy to manufacture from sintered metal and can be molded at low cost. By adjusting the amount to 45 to 65% by weight, the dimensional error after molding is small, the roundness is excellent, and the rigidity at 110 ° C. is also excellent.

[Brief description of drawings]

FIG. 1 is a schematic view of a gas filled cylinder.

[Explanation of symbols]

1 ... Cylinder 3 ... Rod guide 4 ... Through hole 5 ... Piston 6 ... Piston rod

Claims (3)

[Claims] 1. A rod guide for a gas filled cylinder, which is molded from an aromatic polyamide resin containing 45 to 65% of a fiber reinforcing agent. 2. The aromatic polyamide resin comprises a dicarboxylic acid component and a diamine component, the dicarboxylic acid component comprises 60 to 100 mol% of terephthalic acid and 40 to 0 mol% of a dicarboxylic acid other than terephthalic acid, and the diamine component is a fat. The rod guide for a gas filled cylinder according to claim 1, which comprises a group diamine component. 3. The fiber reinforcing agent is glass fiber.
Rod guide for the gas filled cylinder described.